Equine Urinary

Question 1

What are the two main causes of acute tubular necrosis in ARF?

Answer 1

Ischaemia

Nephrotoxins

Question 2

What part of the kidney is most susceptible to ischaemia?

Answer 2

Medulla

Question 3

What part of the kidney is most susceptible to nephrotoxins?

Answer 3

Cortex (filters 90% of blood flow)

Question 4

What should you monitor in horses on potentially nephrotoxic drug therapy?
What does a rise indicate?
Give an example of a nephrotoxic class of drugs

Answer 4

Serum creatinine levels
Significant rise indicates acute tubular necrosis
Aminoglycosides (e.g. neomycin, gentamicin, amikacin)

Question 5

What is azotaemia?

How does it differ from uraemia?

Answer 5

Elevation of blood urea and creatinine

Uraemia is azotaemia with clinical signs present

Question 6

What type of fluids would you use for a horse in acute renal failure?
What is the maintenance requirement for a horse?
How many times maintenance requirement?

Answer 6

Hartmann’s (balanced polyionic crystalloid)
60ml/kg/day (30L/day for a 500kg horse)
2x maintenance

Question 7

What are some clinical signs of chronic renal failure?

Answer 7

Chronic weight loss, poor performance (mild anaemia), lethargy, oral ulcerations, halitosis, PU/PD

Question 8

What do increased elevations in creatinine mean for horses in CRF?

Answer 8

Poor long term prognosis

Shorter survival time

Question 9

What does NSAID toxicity cause in the kidney?

Is it time dependent or dose dependent?

Answer 9

Papillary necrosis

Dose-dependent (c.f. aminoglycosides are time-dependent)

Question 10

What is the main component in uroliths in horses?

Answer 10

Calcium carbonate

Question 11

What is a natural inhibitor of urolith (crystal) growth

Answer 11

Mucous

Question 12

What are the 4 factors contributing to urolith formation?

Answer 12

1. Tissue damage
2. Prolonged transit time
3. Nidus formation
4. Reduced inhibition of crystal growth

Question 13

What are 2 ways to prevent uroliths/calculi returning?

Answer 13

1. Reduce calcium excretion (don’t feed alfalfa)

2. Salt (increases water consumption and diuresis)

Question 14

What are the main 3 differential diagnoses for PU/PD?

Answer 14

1. Renal failure/disease
2. Equine Cushing’s disease (PPID)
3. Psychogenic water consumption
   (Could also be diabetes insipidus - central + nephrogenic)

Question 15

What causes pasture associated (atypical) myopathy?

Answer 15

Sycamore poisoning

Question 16

How do you differentiate between haematuria and haemoglobinuria?

Answer 16

CENTRIFUGE!
In haematuria, the RBCs will form a pellet at the bottom and the supernatant will become clear
In haemoglobinuria, it will be pink/red tinged.